Calculator



June 23, 1942. G. KENDE ETAL 2,287,430

CALCULATOR Filed Dec. 3, 1938 INVENToRs G50/26E KEA/0E BH/L/P J.' BMWA/560MB! A ORNEY Patented June 23, 1942 UNITED STATES PATENT OFFICE CALCULATOR George Kende, New York, N. Y., and Philip J. Brownscombe, East Orange, N. J., assignors to Universal Camera Corporation, New York, N. Y., a corporation of Delaware Application December 3, 1938, Serial No. 243,746 s claims. (ci. zas-:asi

1 tor combination.

Another object of our invention is to provide an improved calculator of the character described, adapted for use with or without a light meter.

A further object of our invention is to provide an improved calculator of the character described' having a novel arrangement of markings and backgrounds whereby to facilitate the speed of operation thereof.

A still further object of my invention is to provide an improved calculator of the character described adapted to be permanently attached to a camera which shall Acomprise relatively few and simple parts, which shall be relatively inexpensive to manufacture, which shall be easy to assemble and to operate, and which at the same time possesses a high degree of efficiency.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the features of construction, combinations of elements,

. and varrangement of parts which will be exemplied in the construction hereinafter described, and of which the scope of application will be indicated in the claims.

In the accompanying drawing, in which is shown one of the various possible embodiments of this invention:

Fig. 1 is a top plan view of a portion of a camera casing with a calculator constructed in accordance with our invention mounted thereon;

Fig. 2 is an end elevational view thereof with the camera casing in section; and

Fig. 3 is a cross-sectional view taken substantially on the line 3-3 of Fig. l.

Referring now in detail to the drawing, there is disclosed a calculator constructed in accordance with our invention, and comprising a top disc-I0, a bottom disc I I and a middle disc I2. It

is noted that the discs I and I2 are substan. tially the same size with the exception of a portion of the middle disc I2 which extends beyond the periphery of the top disc III. The discs I0, II and I2 are arranged in superimposed relationship and are relatively rotatable about a common pivot member I5 which also serves to hold the discs in assembled relationship. The discs I0, II and I2 may be made of any suitable material capable of holding its shape and vsatisfactory for having suitable indicia markings imprinted thereon, such material as for example cardboard, sheet metal or the like.

In accordance with our invention, the calculator is designed to be used independently of a camera, or it may be directly attached to a camera casing as shown in the drawing. In the latterwinstance a portion of the pivot member IFv may pass through the wall of the casing 20 and may be riveted over, as shown, to retain the same in position. If desired, a portion 2l of the wall of the camera casing 20 may be recessed to receive the calculator therein. The recessed area 2l may then be of such size and contour as to snugly receive the bottom disc II therein, the said disc I I being provided with an indented portion forming shoulders 22 to prevent rotational movement of the disc I I for reasons which will soon become apparent.

It is thus seen that the middle and top discs I2 and III respectively may be rotated with respect to the bottom disc and relatively to each other. The discs I2 and III are so designed that after they are rotated to proper position in conformity with the cooperative markings on the three discs they will remain in such position. To this end the middle disc I2 is upwardly dished in a direction towards the top disc III, as clearly shown in Figs. y2 and 3, so that the said disc I2 will act as a spring and thus create friction between itself and the top disc, as well as friction between itself and the bottom disc I I. It is thus seen that in order to relatively rotate the discs I0, I I and I2 it is necessary to overcome the frictional force exerted by the middle disc I2. Therefore, once the discs are properly set they will not rotate of their own accord to disturb the readings.

'I'he middle disc I2 is further designed so that the radius oi friction contact between the middle disc I2 and the bottom disc II is greater than the radius of friction contact between the'middie disc I2 and the top disc Il). Therefore, when the middle disc I2 is rotated, the top disc I0 will rotate with it. When the top disc I0 is rotated, however, the middle disc I2 will not rotate with it, but will be frictionally heldin contact with the bottom plate I2.

'I'he top disc III is adapted to serve as a calculator disc, and the middle disc I2, and bottom disc Il as calculator dials. The three discs I0,

II and I2 are each provided with suitable markings designed to be cooperatively read in the manner soon to be described. Thus, the top disc II! is provided with ya group A of summer light conditions, a similar group B of winter light conditions, a group C of conditions to be used in conjunction with a light meter, a group D of time in seconds values, arranged in 5 degree divisions.

The middle disc I2 is provided with a group i-l of fifteen F opening numbers in equal '5 degree .l is aligned with the pointer of the 2a: filter facdivisions, and a group J of Weston film speed ratings in equal 5 degree divisions.

The bottom disc ll is provided with a group E of winter types of scenes, a similar group G of summertypes of scenes, a group K of filter factors N, 2x and 4x, and a group M of meter numbers 1 to 8 inclusive, corresponding to light meter readings.

it is noted that certain groupings of numbers and markings are arranged in a light color againsta dark background, while certain other groups of numbers and markings are made dark on a light background.

The calculator is so designed that the light background portions of one disc are to be matched with the light background portions of the other discs, in order to simplify the operation of the calculator.

In accordance with our invention, the calcula.- tor described herein is designed to be used in conjunction with a standard type light meter, such as the Weston light meter, or it may be satisfactorily used without the aid of a light meter.

The operation of our calculator for use in conjunction with a light meter will now be described.

The Weston film speed numbers in group J of the middle disc I2 are to be matched with one of the filter factors in group K of the bottom disc I`I. Therefore, the "Weston" film speed of the specific film to be used is first determined (this is usually printed on the lm package) and the` middle disc is turned sothat the Weston" film speed number is aligned with the filter factor of the filter being used. Assuming that no lter is being used and that the Weston film speedl is `.given as 16, the disc I2 is turned to a position Where the indicating pointer, corresponding to the N" position of the group K of the bottom disc I I, points to 16 of the group J.

Further assuming that the picture is being taken on a bright day at sea and lthat the light meter shows a reading of 6, the top disc I0 is turned so that the white pointer of the group C,

identified as Sky-Sea-Snow points directly to the meter number 6 of the group M on the bottom disc II.

By then referring to the "F values of the group H on the middle disc I2, which are to be read in conjunction with the markings in'group D on the top disc III, yit is found that a number of time-inseconds valucs might be used with a correspond- 'ing number of F openings. f

To take another example which may be read in connection with Fig. 1 of the drawing, and

tor in group K of the bottom disc II as shown. It is noted that in group G of the bottom disc II there is an arced section arranged in three steps.

Referring to the outermost step, we read the black letters Sky-Sea-Snow, arranged on a White background. These words are preceded and immediately followed Iby a white and black circular area all and 3| respectively. The area all indicates that the portion of the section covered by the words Sky-Sea-Snow which is nearest to the white disc represents the brightest aspect of the Sky-Sea-Snow condition. As we progress toward the black area 3l, the indication is that the poorer brightness aspect of the Sky-Sea- Snow light condition prevails. This significance of the white and black area is the same in all sections of the light condition portions of the groups G and E of the bottom disc II.

Referring now to the top disc I0, it is noted that here is a summer group A and a winter group B. Assuming now that it is desired to take a street scene on a cloudy summer day at 12 -oclock noon, The next step is to align the black pointer marked "10 a m.2 p. m." in the summer group A with the street scene line nearest the black area in the group G and we get the proper F opening-time-in-seconds combinations read cooperatively on the discs I0 and I2 in the groups D and H. f

To facilitate the lanual rotational movement of the disc I0, there is provided a pair of diametrically opposed roughened areas lll, to cause a gripping action between'the fingers of the operator and the top disc III. Also to facilitate the manual rotational movement of the middle disc I2, there is provided upturned 'projecting portions 42 as shown.

It will thus be seen that there is provided a device in which the several objects of this invention are achieved, and which is well adapted to meet the conditions ofpractical use.

As various possible embodiments might be ma'de of the above invention, and as various changes might be made in the embodiments above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. An exposure calculator for cameras comprising a fiat bottom disc, a flat top disc and a bowed middle disc, said discs being relatively rotatable about a common axis. the apex of said bowed middle disc being in frictional contact with said top disc adjacent said common axis` and the base of said bowed middle disc being in frictional contact'with said bottom disc remote from said common axis so that the frictional contactive force between said middle disc and frictional contactive force between said middle disc and said bottom disc for the purposes set forth.

2. An exposure calculator for cameras comprising a fiat bottom disc, a fiat top disc and a bowed middle disc, said discs being relativelyrosaid bottom disc, said tatable about a. commony axis, said middle disc being sprung between said top and bottom discs, the apex of said bowed middle disc being in frictional contact with said top disc adiacent said common axis, the base of said bowed middle disc being in frictional contact with said bottom disc remote from said common axis, so that the frictional contactive force between said middle disc and said top disc is substantially smaller than the frictional contactive force between said middle disc and said bottom disc whereby rotational movement of said middle disc will cause said top disc to rotate with it and whereby said top disc may be rotated independently of said middle disc and said bottom disc, said bottom disc being provided with a combined subject and light condition scale for winter adapted to be matched and read in conjunction with a combined time-of-theyear and time-of-the-day scale on said top disc, said bottom disc being further provided with a combined subject and light condition scale for summer adapted to be matched and read in conjunction with va combined time-of-the-year and time-of-the-dayscale for summer on said top disc, said middle disc being provided with a film speed rating scale adapted to be matched and read in conjunction with a filter factor scale on top disc being provided bowed middle disc, said with a shutter speed scale adapted to be matched and read in conjunction with a diaphragm opening scale on said middle disc, indicia on said matching scales being similarly colored and disposed in similarly contrasting backgrounds, indicia on different scales Von the samediscs being'` differently colored and disposed on differently colored backgrounds. f

3. An exposure calculator for cameras comprising a flat bottom disc, a fiat top disc and a discs being relatively rotatable about a common axis, said middle disc being sprung between said top and bottom discs, the apex of said bowed middle disc being in frictional contact with said top disc adjacent said common axis, the base of said bowed middle disc being in frictional contact with said bottom disc remote from said Acommon axis, so that the frictional contactive force between said middle disc and said top disc is substantially smaller' than the i'rictional contactive force between said middle disc and said bottom disc whereby rotational movement of said middle disc will cause said top disc to rotate with it and whereby said top disc may be rotated independently of said middle disc an said bottom disc.

GEORGE KENDE. PHILIP J.- BROWNSCOMBE. 

